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to litmus, but gives no stable salts. It is used in the prepara-
tion of malachite green (benzaldehyde green) by heating-
together dimethylaniline, benzaldehyde, and solid zinc chloride.
The product (leuco-malachite green) is then oxidised with lead
peroxide and hydrochloric acid (see p. 216),


HC/..................;                                          /QH5

1^0       II JC6H4N(CH8)2        ->      HO~CrJI4N(CH,),

H JC8II4N(CH3)2                            CflII4N(CH3)2

Leuco-malachite green,


.  ->   HOC£-C6H4N(CHS)2
Base of malachite green.

The latter, in presence of the hydrochloric acid, is converted
into the hydrochloride,

HOCe-CeH4N{CH3)2 -f

HC1 = C^QH4N(CH,).2



Hydrochloride of
malachite green.

Dimethylaniline is also used for the preparation of tetra-
methyldiaminobenzophenone(Michler's compound), which forms
the basis of many colouring matters, and is obtained by acting
upon dimethylaniline with phosgene (see p. 314),

COC12 + 2C6H5N(CH,)o = OC<

+ 2HC1.

Michler's compound.
Nitrosodiraethylaniline. — It is a peculiarity of the
tertiary aromatic amines, which distinguish them from the
corresponding aliphatic compounds, that they are capable of
reacting with nitrous acid. Here the nitroso-group replaces
hydrogen in the para-position to the dimethylami no-group.
The substances, thus formed, are bases, and form salts with
acids, which dissolve in water with a yellow colour. The solu-
bility of the hydrochloride of the nitroso-bases in water
distinguish them from the nitrosamines of the secondary bases?
which are insoluble.               .                                            *